Direct Metal Deposition (DMD) Fabrication Process for Metal 3D Prints

The Direct Metal Deposition is an additive manufacturing technology
using a laser to melt metallic powder. Unlike most of the other
technologies, it is not based on a powder bed but it uses a feed
nozzle to propulse the powder into the laser beam. It is very similar
to Fused Deposition Modeling as the nozzle can move to deposit
the fused metal.

In Direct Metal Deposition, the laser beam and the powder spray are
focused and scan the substrate to deposit the metal. BeAM is one
of the main DMD machine manufacturer.

Principle

As most of the metal 3D printing technologies (
selective laser melting, direct metal laser sintering), this technology is based on the transformation of powdered metal
into a solid metalic object. The main principle is to use a powder
feed nozzle than propulse the powdered metal into the laser beam.
The powdered metal is then fused by the laser. Using a layer by
layer strategy, the
printer head
, composed of the laser beam and the feed nozzle, can scan
the substrate to deposit successive layers. The deposit width is
between 0.6 to 2.4 mm while
the layer thickness lies between 0.2 and 0.8 mm.

Materials

All kinds of metallic materials can be processed by this technology.
Among the most common are steel and aluminum. But very technical
materials are also available such as Nickel based alloys, Titanium,
Cobalt and Copper.

Particularities

Among the laser based metal 3D printing technologies, DMD is the only
one not based on a powder bed. In
SLM and
DMLS, the unfused metallic powder is used as support material and can
be reused. In DMD,
supports can be required to maintain the building object but almost all
the powder is transformed into solid. There is no waste powder
to recycle. This technology also has the ability to comply with
a freeform substrate, a planar building platform is not compulsory.

It can be compared with FDM (renvoi vers la fiche de cette techno →
absente) except that the deposited material can be discontinue,
unlike a plastic
filament.

History

In the first place, Direct Metal Deposition was called Laser Cladding
as it can be used to add a certain amount of metal in order to
repair a damaged part. With the expansion of
3D printing technologies to create near end-use parts, this technology is then also used
as a way to create from the ground an entire object. Then, the
substrate is no longer a part to be repaired but a platform to
start building.

Applications

This technology is mainly used in the aeronautic field to repair complex
and expensive parts instead of replacing them. That way, the manufacturer
saves a spare part and the cost of dissambly and reassembly.

LENS system by Optomec used to repair a metalic part by Direct
Metal Deposition (Image credit: Optomec)

Recently,
MX3D, a Dutch team, used this technology to build a metallic bridge.
The particularity of the project is that the 3D printers were specifically
conceived to move into the building bridge. It is the first bridge
entriely build by robots!

This is how it should look like
during the bridge building (Image credit: 3D natives).

Major manufacturers

One of the first firm to propose this technology is Optomec which patented
their LENS system. Other main actors in this field are Trumpf and
the French company BeAM.

Direct Metal Deposition is mainly used in aeronautics which is one
the main industrial field very active in additive manufacturing,
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